Continuous mixing of viscous materials



June 11 1940. R. v. BURT i GONTINUOUS MIXING OF VISCOUS MATERIALS Filed Sept. 20, 1935 mm wn R INVENTOR. ROBERT M Bu/v:

ATTORNEY;v

Patented June 11, 1940 PATENT OFFICE CONTINUOUS MIXING OF VISOOUS MATERIALS Robert V. Burt, Cincinnati, Ohio, assignor to The Procter It Gamble Company, Cincinnati. Ohio, a corporation oi Ohio Application September 8 Claims- My invention relates to continuous mixing r crutching of viscous substances such as molten soap. This application is a continuation in part oi my application Serial No. 691,257, flled September 27, 1933, now Patent No. 2,024,426, issued December 1'7, 1935.

My invention is particularly applicable ior the continuous addition to molten soap oi those added ingredients of a flowing nature, such as for examplesilicate oi soda solution, sal soda solution, mineral oil, naphtha, 'iatty acids, perfume, and other ingredients'whichare sometimes incorporated in the molten soap to impart various desired properties to the soap product. As ior as I am aware, the mixing oi the soap body and its introduced ingredients heretoiore has been accomplished commercially only by intermittent operation in batches with the use oi machinery usually consisting oi a vessel containing an agitator oi the worm and cylinder type or of the paddle type substantially coming in contact with the sides oi said vessel. Such a method is slower, requires more massive, space consuming, and expensive machinery, and also involves nfore labor and consumes more power than does the continuous method herein described and claimed. In addition to these advantages the employment of my method results in marked improvement in the uniformity oi the mixing and the quality oi the product.

It is an object oi my invention, thereiore, to continuously and uniiormly introduce into a continuously flowing stream oi a viscous substance, such as soap, an added ingredient of a fluid nature, or a plurality of same, in predetermined proportion and to continuously crutch the mingled constituents on their passage to finishing machinery which in the soap industry constitute solidifying irames, cooling rolls, drying rolls, spray drying apparatus, or other apparatus, depending upon the iorm which the finished soap is to have.

One of the necessary features of my process is to insure during the continuous intermingilng oi the ingredients a maintenance oi a desired proportion between the quantities oi the ingredients in order that the finished mix will be uniiorm and have the required properties. Furthermore I find it necessary to maintain the viscous material and the ingredient or ingredients intermingled therewith in their passage to the mixer under substantially uniiorm pressure in the course of operation, even though the rate of operation may vary or the flow through the apparatus entirely stop. As a further saieguard I prevent the M, 1935, Serial No. 41,651

introduction oi the wrong proportion oi the main ingredient in case oi chance stoppage or decrease in the proportion oi the secondary ingredient below a given limit.

In the practice oi my invention as applied to the crutching oi molten soap, ior example, a continuously flowing stream oi molten soap as received from the soap boiling kettle or other source and a continuously flowing stream oi added ingredient or a plurality oi same are accurately proportioned, combined, and the mingled substances conducted to an enclosure provided with suitable means ior continuously eiiecting the desired mixing or crutching oi the soap and added ingredient on the passage of the materials to subsequent soap finishing operation.

Any type of combined proportioning device and mixer at suitable construction may be employed provided that the ingredients are accurately proportioned continuously and that the mixer has .0 sufllcient capacity to eiiect the desired mixin while the constituents are passing therethrough in a continuous stream. The apparatus which I prefer to use is characterized by its simplicity, accuracy, flexibility, and its eiiectiveness in acg5 complishing the desired result, and is illustrated and described in detail in my co-pending application Serial No. 691,257, new Patent No. 2,024,- 425, oi which this application is a continuation in part. a

For purposes oi illustration the process is shown diagrammatically in Figure 1 wherein only those details necessary ior thecomplete understanding of the process are included. 2 represents a conduit through which the viscous sub- ,5 stance, in the present instance molten soap, is conducted from the supply tank I through valve I to the apparatus. 5 designates a positive displacement pump, such as ior example a well known gear type pump, having a by-pass I 40 which extends irom the outlet 1 to the inlet 8 oi the pump 5 and which contains therein an automatically acting relief valve 9. Conduit Ill conducts the molten soap through a solenoid controlled valve 31 and a pressure regulating diaphragm operated valve Ii, to a rotatable member I! which may be any type oi meter and which rotates in direct relation to the amount of molten soap flowing therethrough. The meter II is equipped with a by-pass I! to be used in cleaning operations, which by-pass is controlled by manually operated valves Ii, II and It. The rotating action oi the rotatable member I! is'transmitted mechanically to a power ampliiying means I! whose speed oi rotation is controlled by, u

the rotatable member I! and whose power output is controlled by motive means II. II indicates a pump for delivering an added ingredient,

' hereinafter referred to as a secondary ingredient,

The pump is driven by power amplifying means ll through suitable permanent or change speed connections and is similar in construction to pump I, previously described, in that it is positive acting and delivers the secondary ingredient in direct proportion to its speed of rotation. The pump is fed with the secondaryv ingredient from storage supply tank 2., the pump then forcing the secondary ingredient through conduit 2i and check valve 2 is into conduit 22 which is conducting the molten soap and which then conducts the mingled ingredients through the diaphragm compartment 28 of valve ii to mixing device 24. This additional pressure regulating valve is not described in my application of which this is a continuation in part. Its function is to provide additionally for a constant pressure during the proportioning step. Although in the present embodiment I have indicated the use of only one ingredient introducing pump, it will be understood that a plurality of same may be driven in a manner described above without departing from the spirit of my invention.

It will be obvious that the proportion of secondary ingredient to soap must be maintained substantially constant for any predetermined set of operating conditions. It is therefore necessary that the effective rates of discharge of the pump I and the secondary ingredient pump it be kept at a constant ratio. This is true irrespective of the absolute rate. The rate of discharge of the soap pump 5 may increase or decrease but the rate of discharge in the secondary ingredient pump must always increase or decrease in the same proportion.

To insure such accurate operation and proportioning, I have provided the metering device I! which is driven by the soap forced through the apparatus under pressure by pump 5 as described above, and which through suitable connections governs the rate of operation of the pump it. Because of the delicacy and sensitiveness of the meter II, it is advisable that this device operate with as little resistance to its rotation as possible. For example, if the device I I were depended upon as the only motive means for the secondary ingredient pump, which of course requires the expenditure of considerable energy with consequent resistance to the free rotation of device 12, then the sensitiveness of the device I; to fluctuations in the flow of soap would be reduced to such an extent that the value of the device for insuring corresponding effective rates of operation of the soap pump and the secondary ingredient pump would be practically lost. In my process, therefore, the power developed by the metering device I! in its rotation is amplified by meansof a power amplifying mechanism H such as that now known in the art of power transmission as a torque amplifier and the power thus developed is employed to operate the ingredient introducing pump ll. One device of the type referred to is that invented by Henry W. Nieman and covered in Patent No. 1,751,652, issued to him on March 25, 1930. Since this torque amplifier includes a number of structural elements and has a method of operation which would require arather lengthy description, it is deemed sufiicient to merely illustrate it at I! as shown in Figure 1. .As already pointed out, the power delivered to the secondary ingredient pump II. must be suiiicient to insure the satisfactory operation of the pump and in the instant case is supplied by motive means ll through power amplifying means .il in direct proportion to the speed of rotation of metering device it. At all times the power transmitted from the motor through the power amplifying means to the pump II is delivered at a speed controlled by the speed of rotation of the device if, the light torque and sensitiveness of this meter insuring an accurate correspondence between the rates of operation of the secondary ingredient pump II and the flow of the soap which is driving the device It.

Mixing device 24 is operated by some external motive means, either by a separate motor or by the motive means is supplying the power to the power amplifying means II. This mixing device may be of any well known type of construction,

but I have found that the desired mixing and homogeneity is produced if a device similar to that described in my U. S. Patent No. 2,024,425 is used which acts to repeatedly divide the commingled ingredients as they pass through restricted passages. Likewise, I have used in my continuous crutching operation with'satisfactory results a positive displacement gear pump with a by-pass 2i and relief valve 26 constructed in a similar manner to that previously described in the case of pump i. Under conditions where the crutched soap must be conveyed over a relatively long distance, or where it is desired to deliver the crutched soap to finishing machinery under higher pressures than the proportionometer can withstand, the gear pump type of mixer is to be desired. The pump in this case acts not only as a mixer, but also as a booster pump. It will be noted that as the mingled ingredients pass through such a pump the said ingredients are repeatedly divided by the internal working mechanism of same, as they pass through a restricted passage. I do not described such a pump in my co-pending application heretofore referred to.

Another feature of my method is the flexibility of operation. The amount of material fed to the finishing machinery by the crutcher apparatus may be controlled by a manually operated valve 21 inserted in the discharge line of mixer 24 in some position convenient to the operator controlling the continuous crutching operation. By means of this valve, the output of the apparatus may be varied from zero to the full capacity of the pumps introducing the ingredients without any variation in the relative proportions of the ingredients. It will be noted that I have provided a check valve 21a beyond the valve 21 in the exit line fnomthe mixer in order to prevent material from backing up into the apparatus in case of excessive external pressure.

It is important to note that operation on viscous substances such as soap according to my method is accompanied by certain difficulties not encountered in the continuous mixing of substances that are. truly free flowing liquids. Difficulties, which are not usually met in mixing two or more ingredients having approximately the same specific gravity are also encountered in crutching soap and the usual type of builder. For example, molten kettle soap is .not a true liquid normally, but is of the nature of a thick, viscous paste which will congeal ion cooling. Also, silicate of soda solution, commonly employed as a builder for soap as hereinbefore noted, is a heavy viscous liquid, nearly half again as heavy as soap, which will crystallize at low winter temperatures and will solidify into a hard, glassy abrasive substance upon drying in air.

Because of the above described properties of the materials commonly used, great care must be taken to insure that they are in flowing con- The difi'erence in specific gravity, which, in comparing soap with silicate of soda, may be as much as fifty per cent, involves careful provision against Stratification of the heavier silicate of soda in the lighter soap body. By my method I, have provided for complete and uniform dissemination and mixing of substances of greatly differing specific gravities, while conducting the material at a rapid rate through the apparatus.

I also find it convenient to practice my invention under positive pressure and to control the pressure by means of the relief valve 9 and the diaphragm valve II. By means of the relief valve 9 it is possible to vary the output of the apparatus without affecting the driving mechanism for the pump 5, thereby obtaining a source of supply similar to gravity feed under constant head. If the outlet of the apparatus should be entirely closed, there will be no passage of material through meter l2 and the entire amount of said material delivered by pump will be returned to the inlet of the pump by means of the by-pass 6.

As is well known, the accuracy of measuring gear pumps, such as that described herein for the introduction of the secondary ingredient, is markedly improved if the pressure against which the pumps operate is maintained substantially constant. I accomplish this desired condition by the use of the diaphragm valve H in conjunction with the pump 5 and its associated by-pass 6. As shown in Figure l, the diaphragm portion 23 of the valve is subjected to the pressure in the conduit conducting the intermingled constituents to the mixer 24 and is directly connected in a suitable manner to the stem 29 of the valve H. The mechanism is so constructed that movements of the diaphragm, occasioned by variations in pressure in the conduit, open or close valve l I in order to maintain the pressure against the diaphragm substantially constant. The operation of the device will be readily understood. A throttling of valve 21 will increase the pressure in the conduit conducting the molten soap, provided of course the pump 5 is not already delivering soap at the pressure at which relief valve 9 will operate. With increase in pressure the movement of the diaphragm 23 will be in opposition to the spring 29 and through stem 29 will effect partial closure of valve ll, thereby reducing the fiow of soap to the inlet of the meter l2 and thus reducing the pressure of same in the conduit beyond valve ll. Movement of the diaphragm 23 and thus a throttling of valve II will continue until a state of equilibrium is reached between the pressure in the conduit and the compression of the spring 29, at which point the desired pressure in the conduit will be attained. Upon opening valve 21, the pressure on the diaphragm will decrease moving the diaphragm and valve stem so as to open valve II and increase the pressure in the conduit. Movement of the diaphragm will contime until equilibrium is established between the coiled spring and the pressure against the diaphragm, whereupon the pressure is obtained against which it is desired to operate the secondary ingredient pump I9. Thus, in my invention the use of the two valves 9 and H, respectively, will insure a substantially constant pressure against which the added ingredient pump l9 operates. The diaphragm valve per se and its operation is not novel with me. My invention in part resides in the use of same to improve methods of proportioning and mixing as applied to viscous materials similar to molten soap.

As described in my U. 8. Patent No. 2,024,425,

*I prefer to provide for the chance stopp e or a decrease in the proportion of secondary ingredient below a predetermined limit. Although the device l2 and its power amplifying means connection insure proper correspondence of the quantities of soap and of the secondary ingredient, as long as the pump I9 and other parts of the secondary ingredient supply system are in proper working order, the apparatus would not function properly should the pump ill for any reason fail to supply the required amount of secondary ingredient, notwithstanding that its proper speed was maintained through the operation of the meter i2 and the power amplifyL'ig means I1.

As indicated in Figure 1, the discharge line 2| of the secondary ingredient pump l9 contains a pressure gage 39. This gage 39 is provided with a dial in accordance with the usual custom, which will indicate the pressure of supply of the secondary ingredient, and which also includes two adjustable electrical contact elements 3| and 3.2 through which an element 33 moved by the pressure gage will complete a circuit including wire connections 34 and 35 andthe coil 39 of the solenoid valve 31. The sliding core or a mature 38 of this solenoid is connected to the .em of valve 31 interposed in the conduit I9 between the main pump 5 and the rest of the apparatus. The parts are adjusted so that when the pressure in the secondary ingredient conduit 2| falls below a predetermined limit the element 33 of the gage 39 will contact the elements 3| and 32, thus closing the electric circuit and effecting movement of the core 39 of the solenoid 36 so as to close valve 31 and stop the fiow of soap, the pump 5 by-passing as hereinbefore described. Thus, in my invention, it is practically impossible to force soapthrough the apparatus without supply of a secondary ingredient in the predetermined proportion.

The well known step of crutching air into the molten soap in measured quantities or otherwise so as to make the soap lighter in color and in specific gravity may also be made a part of my process by introducing the air into the combined constituents on the inlet side of the mixing device. However, in the claims reference to an added ingredient is not intended to include air or similar gas.

With my improvedmethod only about one and one-half horsepower is required for delivering about 4800 pounds of crutched soap per hour as compared with about horsepower heretofore required with the usual soap crutching apparatus. The space occupied by the apparatus used according to my method is about one foot in width,

about a foot in height and about fivefeet in length compared with two of the usual crutchers ten soap which comprises causing molten soap necessary for the same output, each about five to flow under pressure through a conduit, causfeet in diameter and about five feet high. The ing said flowing soap to develop power at a use of scale tanks or other means for weighspeed proportional to the flow of said molten ing out the ingredients may be dispensed with. soap, amplifying said power without altering Previous methods have required the use of pipe said speed, continuously and uniformly at all about four inches in diameter. Much smaller piping, for-example one inch in diameter, is permissibleintheapparatususedinthepracticeof my invention. Valves and fittings are correspondingly reducedin aise, thus effecting a savingnotonlyinflrstcost,butalsointhecostof maintenance. Since my improved apparatus is easily cleaned by the introduction of live steam or hot water, I avoid the troublesome scraping which is frequently necessary with crutchers heretofore used in the soap industry, as above described.

Other advantages of my method have been alluded to in the description herein given and it will be understood that these may be obtained in greater or less degree without departing from the principle of my invention. The preferred example of my method has been rather specifically disclosed as is necessary, but it will be understood that modifications such as have been alluded to herein, or other modifications not mentioned herein, may occur in practice and under different conditions thatmay be encountered, and therefore I am not limited to such precise disclosure, but what I claim as new and desire to secure by letters Patent is:

l. The method of mixing or crutching molten soap, which comprises passing the soap under prasure through a conduit, continuously and uniformly at all rates of flow forcing an added ingredient into the passing soap in a maintained proportion to the quantity of soap passing, delivering the commingled soap and ingredient from the conduit through a restricted enclosure wherein the soap and added ingredients are mechanically admixed and varying the rate of passage of the soap and ingredient by restricting the outflow from said enclosure while maintaining a constant premure of the commingled soap and ingredient toward said enclosure at all rates of flow.

2. The process of continuously crutching molten soap, which comprises causing soap to flow continuously and to actuate moving means in accordance with its flow, amplifying the power developed by the passage of said soap through said moving means with the addition of power from an external source, continuously and uniformly at all rates of now forcing an added ingredient into the passing soap by means of said amplified power in a predetermined proportion to the quantity of soap passing, and thereafter subjecting the flowing soap and added ingredient to a continuous mixing action.

3. The process of continuously crutching molten soap which comprises causing molten soap rates of flow forcing by means of said amplifled power an added ingredient of fluid nature into the flowing stream of molten soap in predetermined proportion to the quantity of soap flowing, subjecting the flowing soap and added ingredient to a continuous mixing action and controlling the flow of the resulting mixture subsequent to said mixing action.

5. The process of continuously crutching mol ten soap which comprises causing molten soap to flow under pressure through a conduit, causing said flowing soap to develop power at a speed proportional to the flow of said molten soap, amplifying said power without alte'ring said speed, continuously and uniformly at all rates of flow forcing by means of said amplifled power an added ingredient of fluid nature into the flowing stream of molten soap in predetermined proportion to the quantity of soap flowing, subjecting the flowing soap and added ingredient to a continuous mixing action, controlling the flow of the resulting mixture subsequent to said mixing action and maintaining a substantially constant pressure of said mixtures towards said mixing action at all rates of flow.

6. In the process of proportioning and mixing a viscous material similar to molten soap with a secondary ingredient of fluid nature, the steps which comprise causing a viscous material to flow under pressure through a conduit, causing said viscous material to develop power at a speed proportional to its flow, amplifying said power without altering said speed and continuously and uniformly at all rates of flow forcing by means of said amplified power an added ingredient of fluid nature into the flowing stream of viscous material in predetermined proportion to the quantity of viscous material flowing.

7. In the process of proportioning and mixing a viscous material similar to molten soap with a secondary ingredient of fluid nature, the steps which comprise causing a viscous material to flow under pressure through a conduit, causing said viscous material to develop power at a speed proportional to its flow, amplifying said power without altering said speed, continuously introducing by means of said amplified power an added ingredient of fluid nature into the flowing stream of viscous material in predetermined proportion to the quantity of viscous material flowing and automatically stopping the flow of said viscous material when the proportion of said added ingredient falls below a predetermined limit.

8. The method of proportioning and mixing a viscous material with an added ingredient, which comprises passing the viscous material under pressure through a conduit, continuously and uniformly at all rates of flow forcing an added ingredient into the passing stream of viscous material in a maintained proportion to the quantity of viscous material passing, delivering the commingled viscous material and added ingredient from the conduit through a restricted enclosure wherein the commingled materials are mechanically admixed and varying the rate of e of the commingled materials by restricting the outflow from said enclosure while main-= taining a constant pressure of the commingled materials toward said enclosure at all rates of flow.

9. In the process of continuously proportioning and mixing a viscous substance similar to molten soap with a secondary ingredient of fluid nature, the steps which consist in continuously metering the flow of said viscous substance, continuously introducing a flowing stream of a secondary ingredient into the flowing stream of said viscous substance in substantially constant predetermined proportion as controlled by said metering step, measuring the pressure of the combined streams and automatically controlling the flow of the viscous substance toward said metering step in accordance therewith whereby a constant pressure is maintained at the point where the secondary ingredient is introduced. ROBERT V. BURT. 

